The present invention relates to a dispenser for a roll of web material, and particularly to an electric dispenser that automatically dispenses individual sheets from a roll of perforated web material.
A number of dispensing devices are well known in the art for dispensing and cutting rolls of web material such as paper toweling. With certain of these dispensers, the process of dispensing and cutting the web material is carried out automatically by a user pulling on the free “tail” end of the web material that extends from a dispensing slot in the apparatus. In a typical configuration, the web material is engaged against a rough friction-enhancing surface of a feed drum and the action of pulling the web tail causes the drum to rotate. The drum includes a drive mechanism and, after the initial pull on the web tail by a user, the drum is driven a predetermined rotational degree to dispense a metered amount of the material. A cam driven cutting mechanism may be provided in the rotating drum that pivots out of a slot in the drum to automatically cut the web at the proper length. The dispensers typically include a stored energy mechanism, such as an eccentric cam, that is spring loaded during the initial rotation of the feed drum, and causes the drum to continue to rotate after the web has been cut. This action causes an additional length of the web material to be feed out of the dispensing slot as the tail for the next dispensing sequence. These types of dispensers are commonly referred to as “no-touch” or “sanitary” dispensers because the user does not manually operate any portion of the drive or cutting mechanism and does not actually have to touch the dispenser. The user only touches the tail end of the web material.
Although effective, the conventional mechanical sanitary dispensers utilizing automatic mechanical cutting and feeding mechanisms can be relatively complicated from a mechanical component standpoint and expensive to manufacture and maintain. Also, some users have noted that such dispensers present an inordinate amount of resistance to pulling a towel from the dispenser. This may be particularly true when the initial pulling action by the user must also provide the force needed to load a spring of the automatic tail feeding mechanism. Thus, web materials with relatively high tensile strength must be used with such dispensers.
Advances have been made in the art relating to electronic sanitary towel dispensers as well. With such dispensers, the unit is typically activated upon detection of motion of a user's arm or hand. A motor is subsequently energized through a control circuit and power source to drive a feed roll and thus dispense a measured length of material. The user then grabs the exposed material and pulls it at some angle to the dispenser cover causing the sheet of material to separate on a cutting edge or serrated tear bar. The cycle is repeated for the next user.
U.S. Pat. No. 3,730,409 discloses an electronic dispenser wherein initially a full measured length of towel hangs out of the dispenser. A user grabs and separates the towel by pulling it against a tear bar. A force activated switch is configured with the tear bar that activates a dispenser motor through a power source and electronic circuit upon the user tearing the towel. The motor then drives a feed roll to deliver a full measured length of towel material outside of the dispenser cabinet where it hangs for the next user to grab and tear. WO 00/63100 describes an electronic dispenser with a similar operating principle. These dispensers have the disadvantage that the entire towel sheet hangs out of the dispenser prior to use. This is obviously not a sanitary or desirable condition.
Advances in paper making technology allow for relatively easy formation of perforations in sheet material, and a number of dispensers are known for dispensing rolled sheet material having spaced rows of preformed perforations. Such perforations weaken the sheet material, making it easier to separate an individual sheet from the remainder of sheet material. For example, U.S. Pat. No. 6,412,679 describes a motorized dispenser for dispensing sheets from a roll having spaced perforation lines. A sensor detects removal of a dispensed sheet before permitting a subsequent dispensing cycle, and also senses the leading edge of the sheet and meters the amount dispensed in order to maintain registration with the perforations. The user must grasp the dispensed sheet and tear the material along the perforation line.
U.S. Pat. No. 5,205,454 describes a dispenser wherein the sheet material is separated into individual segments by perforated tear lines which are shaped to incrementally pass through a nip formed by nip rollers due to a pulling force exerted on an end-most segment by a user. A drag force opposed to the pulling force is exerted on the sheet material by the nip rollers so that the tear line tears as it passes through the nip. Tearing along the perforated tear line is not completed until a portion of an adjacent segment is presented for pulling by a subsequent user.
U.S. Pat. No. 6,766977 describes a dispenser for dispensing individual sheets from a dispenser containing a source of sheet material having a plurality of spaced perforations. The dispenser includes at least one rotatable roller, a rotation monitor configured to monitor the amount of rotation of the roller to thereby determine the amount of sheet material traveling downstream from the roller, a perforation sensor for sensing perforations in the sheet material, and an outlet for dispensing sheet material. The amount of rotation of the roller is detected and the advancing of the sheet material is stopped when the roller rotates a first predetermined amount and a perforation is detected. The user must grasp the dispensed sheet and tear the material along the perforation line.
The perforated sheet material dispensers, such as those described above, have the disadvantage that the sheets are ultimately separated by the user grasping and pulling on the exposed sheet with sufficient force to separate the material along the perforation line. This necessitates structure and relatively complicated control circuitry to ensure that the perforation line is aligned or registered at a precise location with the housing, and for breaking rotation of the feed roller so that the necessary force is generated for tearing the material. Stretching or slipping of the web material, or tearing of the web material at a location other than at a perforation line, may prevent further operation of the dispenser.
The present invention relates to an improved electric dispenser for perforated sheet material that eliminates that addresses at least some of the drawbacks of conventional mechanical and electrical perforated sheet material dispensers.